Arctic, Northwest to Northeast Pacific: drainages from Point Hope, Alaska to Ventura River, California, USA; occasionally strays south to San Diego in California, USA. Also in Honshu, Japan (Ref. 6793), Sea of Japan (Ref. 1998), Bering Sea (Ref. 2850) and Sea of Okhotsk (Ref. 1998). Found in Coppermine River in the Arctic. Several countries report adverse ecological impact after introduction.

Dorsalspines
(total): 0;
Dorsalsoft rays
(total): 10-14;
Analspines: 0;
Analsoft rays: 13 - 19;
Vertebrae: 67 - 75. Distinguished by the small black spots on the back and on the upper and lower lobes of the caudal fin, and the black gums of the lower jaw (Ref. 27547). Body fusiform, streamlined, noticeably laterally compressed in large adults, somewhat deeper than other species (Ref. 6885). Gill rakers wide-spaced and rough; pelvic fins with axillary process (Ref. 27547). Fish in the sea are dark greenish to blue black on top of head and back, silvery to white on the lower sides and belly; numerous small, dark spots along back and upper sides and on both lobes of caudal; gum line of lower jaw black (Ref. 27547). In fresh water, with the approach of the breeding condition, the fish change to olive brown, red or purplish, the color change being more marked in males than in females (Ref. 27547).

Biology
Glossary
(e.g. epibenthic)

Adults return to natal streams from the sea to spawn (Ref. 27547). Fry may migrate to the sea after only 3 months in fresh water, some may stay for as long as 3 years, but generally most stay a year in the stream before migrating (Ref. 27547). Some individuals remain close inshore throughout their lives, but some make extensive migrations (Ref. 27547, 44894). Also found in lakes (Ref. 1998). Possibly up to 375 m depth (Ref. 6793). Epipelagic (Ref. 58426). Food in streams is mainly terrestrial insects and small crustaceans; in the sea, major food items include fishes, crustaceans, and other invertebrates (Ref. 27547). Young are preyed upon by fishes and birds (such as mergansers and kingfishers); adults are prey of large mammals and large birds (Ref. 1998). Highly regarded game fish (Ref. 27547). Flesh is usually red, but some are white; the red meat commands a higher price (Ref. 27547). Marketed fresh, smoked, frozen, and canned. Eaten steamed, fried, broiled, boiled, microwaved, and baked (Ref. 9988). Viscera said to contain high vitamin A content and used successfully as food for hatchery fish (Ref. 28971, 28977).

Adults migrate up to 4,827 km upstream to spawn (Ref. 6850). Migration from the sea begins in December so that the the first fish are near river mouths by spring (Ref. 27547). Once a female selects a spot, she begins to dig a nest, driving away other females during the period of nest building. The female is attended by a larger, dominant male and several smaller males who drive away other males. While the female digs the nest, the male courts her by coming to rest beside her and quivering; by swimming about over her, touching her dorsal fin with his body and fins; and occasionally nudging her side gently with his snout (Ref. 28978). Upon completion of the nest, the female drops into it and is immediately joined by the dominant male. The fish open their mouths, vibrate, and eggs and sperm are released. At this point smaller males may dart into the nest and release sperm. The female then quickly moves to the upstrem edge of the nest and begins to dig. The eggs are covered and a new nest is made. The whole process is repeated until the female releases all her eggs, which may take several days. The male then leaves the female and may mate with another female. The female guards the nest for as long as she can. Spent adults usually die a few days after spawning. (Ref. 1998, 27547).
Reproductive strategy: synchronous ovarian organization, determinate fecundity (Ref. 51846).